Re: [amsat-bb] SO-50 & frequency stability as of late
Twice during the 1655Z pass just now I actually had to shift UP in frequency to hold the downlink. Right at AOS I picked up the signal at .795, made a contact, and about 30 seconds later I heard a very noticeable 'shift' in the noise where it was basically unreadable. I shifted down, it got worse, so I went up and picked it back up at .800 clear as a bell. About 6 minutes later, near my apex, I had followed the doppler down normally to about .780, and it jumped back up again by about another 5 or so. Each time it did this, it was in the middle of someone else's transmission and there was an abrupt 'shift' that didn't sound anything like the gradual worsening that I normally hear with doppler.
Just my observations from a sat-noob. Also first post on amsat-bb... o/
73, Dave, KG5CCI
On 9/8/2014 11:30 AM, Alan wrote:
Clayton,
I have been watching it shift 5-10 KHz or so on some passes, though 3-5 KHz is more common. Watching it with a DSP rig allows you to compensate.
The more interesting question is what, if anything, the uplink is doing? I got up for a 0200 L pass to experiment, and there was nobody else on. I thought I had it figured out, and suddenly the downlink shifted. Then, my uplink data seemed wrong, as if it also shifted. ;( Will try again the next time I have some insomnia.
73s,
Alan
WA4SCA
<-----Original Message----- <From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Clayton Coleman <Sent: Monday, September 08, 2014 10:54 AM <To: AMSAT-BB <Subject: [amsat-bb] SO-50 & frequency stability as of late < <I have been noticing some irregular shifts in SO-50's downlink <frequency the past several days. I noticed it in the past but it's <been a while since this occurred. Several others are reporting it as <well. < <At my AOS today (15:12 UTC, orbit # 62976), SatPC32 had predicted the <downlink to be near 436.801 MHz, when in fact I was receiving the bird <at 436.793. It proceeded to jump up to 436.795 at my TCA before <making it's way down to 436.780 near my LOS. < <This seems to be posing some issues for people using full computer <control and also those who stick to pre-programmed memory channels to <make frequency adjustments during a pass. < <Considering this recent frequency instability, I would recommend you <manually tune for the strongest downlink frequency. This would help <eliminate some issues with stepping on stations engaged in existing <QSO's. An alternative would be to try using RIT if you insist on <computer control. < <The old rule applies -- if you can't hear, don't transmit. < <73 <Clayton <W5PFG <_______________________________________________ <Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available <to all interested persons worldwide without requiring membership. Opinions expressed <are solely those of the author, and do not reflect the official views of AMSAT-NA. <Not an AMSAT-NA member? Join now to support the amateur satellite program! <Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Yep. It's really been dancing around lately.
This seems to be something that surfaces every few months. Interestingly, I found the last time I noted this drift was around June 1st. I ran pass predictions and found that passes were occurring right about the same time then as they are now.
73,
Paul, N8HM
On Mon, Sep 8, 2014 at 2:18 PM, Dave Swanson dave@druidnetworks.com wrote:
Twice during the 1655Z pass just now I actually had to shift UP in frequency to hold the downlink. Right at AOS I picked up the signal at .795, made a contact, and about 30 seconds later I heard a very noticeable 'shift' in the noise where it was basically unreadable. I shifted down, it got worse, so I went up and picked it back up at .800 clear as a bell. About 6 minutes later, near my apex, I had followed the doppler down normally to about .780, and it jumped back up again by about another 5 or so. Each time it did this, it was in the middle of someone else's transmission and there was an abrupt 'shift' that didn't sound anything like the gradual worsening that I normally hear with doppler.
Just my observations from a sat-noob. Also first post on amsat-bb... o/
73, Dave, KG5CCI
On 9/8/2014 11:30 AM, Alan wrote:
Clayton,
I have been watching it shift 5-10 KHz or so on some passes, though 3-5 KHz is more common. Watching it with a DSP rig allows you to compensate.
The more interesting question is what, if anything, the uplink is doing? I got up for a 0200 L pass to experiment, and there was nobody else on. I thought I had it figured out, and suddenly the downlink shifted. Then, my uplink data seemed wrong, as if it also shifted. ;( Will try again the next time I have some insomnia.
73s,
Alan
WA4SCA
<-----Original Message----- <From: amsat-bb-bounces@amsat.org [mailto:amsat-bb-bounces@amsat.org] On Behalf Of Clayton Coleman <Sent: Monday, September 08, 2014 10:54 AM <To: AMSAT-BB <Subject: [amsat-bb] SO-50 & frequency stability as of late < <I have been noticing some irregular shifts in SO-50's downlink <frequency the past several days. I noticed it in the past but it's <been a while since this occurred. Several others are reporting it as <well. < <At my AOS today (15:12 UTC, orbit # 62976), SatPC32 had predicted the <downlink to be near 436.801 MHz, when in fact I was receiving the bird <at 436.793. It proceeded to jump up to 436.795 at my TCA before <making it's way down to 436.780 near my LOS. < <This seems to be posing some issues for people using full computer <control and also those who stick to pre-programmed memory channels to <make frequency adjustments during a pass. < <Considering this recent frequency instability, I would recommend you <manually tune for the strongest downlink frequency. This would help <eliminate some issues with stepping on stations engaged in existing <QSO's. An alternative would be to try using RIT if you insist on <computer control. < <The old rule applies -- if you can't hear, don't transmit. < <73 <Clayton <W5PFG <_______________________________________________ <Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available <to all interested persons worldwide without requiring membership. Opinions expressed <are solely those of the author, and do not reflect the official views of AMSAT-NA. <Not an AMSAT-NA member? Join now to support the amateur satellite program! <Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Sent via AMSAT-BB@amsat.org. AMSAT-NA makes this open forum available to all interested persons worldwide without requiring membership. Opinions expressed are solely those of the author, and do not reflect the official views of AMSAT-NA. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
participants (2)
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Dave Swanson -
Paul Stoetzer